1. Line muffin tins with paper liners. Spray the inside of the liners with non-stick baking spray.
2. Whisk dry ingredients: cocoa(s), flour, brown sugar, baking powder, baking soda, and chocolate chips in large mixing bowl. Set aside.
3. Add eggs, milk, vanilla and melted butter to the blender jar. Process on LOW until smooth.
4. Add a small portion of the dry ingredients to the mixture while the blender is not in operation. Blend the mixture on low. Stop the cycle and continue to repeat this process until all dry ingredients have been added. If necessary, use a spatula to scrape the ingredients along the side of the jar while the blender is not in use.
5. Use a spoon or a 1-1/2” ice cream scoop to add batter to each muffin liner.
6. CONVECTION BAKE for 20 to 25 minutes or until a toothpick inserted into the center comes out clean.
7. Allow muffins to stand for 15 minutes before serving.
8. Freeze muffins for up to 3 months in an airtight storage container